It is typical to customize a satellite for a particular country or geographic area based on a given orbital location of the satellite. This limits the satellite to use only for that specific application. If a situation arises where it becomes necessary to change geographic areas, a newly configured satellite must be launched in order to effect change.
In the case of a malfunction of a satellite, another satellite must be built to a similar performance specification. This can result in a delay of up to three years, for the build and launch of the replacement satellite. A reconfigurable antenna system would alleviate some of the drawbacks associated with area specific satellite systems.
There are complex approaches to achieving efficient reconfigurable antennas. However, these approaches have limited efficiency due to current amplifier designs. While in the future this approach may be possible with better amplifier designs, it is not yet practical to employ active antennas.
A rotatable antenna beam may be accomplished by rotating a subreflector in a Gregorian dual reflector. The subreflector is initially shaped to generate a simple elliptic beam. However, the beam size is limited to about 3 to 4 degrees, since the subreflector shaping is limited in its capabilities. This is a disadvantage because many current day C-band beams are very large. Another drawback is that subreflector shaping limits the beam shapes to simple shapes, and most applications require complex beam shape capability.